I wanted to make the Indian-Spiced Shepherd's Pie but I have ground coriander and ground white pepper at home. Could I use these instead of the seeds and, if so, what quantities of each? Thanks!
Nigella's Indian-Spiced Shepherd's Pie (from SIMPLY NIGELLA) uses peppercorns in the sweet potato topping and a spice mixture including cumin in the lentil filling. Whole spices tend to have a fresher and stronger taste than ready ground ones and tend to keep better, so if possible we would prefer to use the whole spices for this recipe.
However it is possible to use ground alternatives, if that is all that you have to hand. For the peppercorns we would suggest cooking and mashing the sweet potatoes without the peppercorns and then adding a few pinches of ground white pepper, tasting between each addition, until you get a pungency that suits your taste. For the cumin you would usually allow ½ to ¾ teaspoon of ground spice per teaspoon of whole seeds. So you would need to use 1-1½ teaspoons of ground cumin - it depends on how fresh your ground cumin is but if it is very fresh then use the lower quantity. Add the ground cumin to the other spices once they have been ground or chopped in step 4.